From The Manufacturer/Wikipedia/People Smarter Than Us:
The DDM4v1, the original Daniel Defense Rifle, is built with a Cold Hammer Forged 16” M4 Profile barrel with a Carbine gas system. It comes installed with our proprietary front sight base which is precision CNC machined from a solid billet of 4140 steel. This FSB features a serrated curved design to minimize glare and is salt bath nitride treated minimizing corrosion and wear.